Flash EPROM endurance simulation using physics-based models

Abstract

A novcl unified ficld-dependent oxide charge generation (FDG) model is introduced to consistently simulate oxide degradation due to Fowler Nordheim (FN) tunneling and hot carrier injection (HCI) stresses over a wide range of oxide field intensity. This model, combined with an interface charge generation model, is used to study effects of stress-induced interface and oxide charges on flash device erase and programming speeds, hand-to-hand tunneling leakage current, and threshold voltage shift. An cfficient cycle-weighting method is introduced to simulate flash device programming/erase ( P E ) cycle endurance. Excellent agreement has been achieved between the simulation predications and experimental data over various operation conditions without parameter fittings or preassumed interface and oxide charge distributions. Simulation results show that the endurance characteristics are mainly affected by both the PE gate current reduction due to oxide charges and the flat-band voltage increase due to both oxide and interface charges.

Simulation on endurance characteristic of charge trapping memory

“…where α is a fitting constant and β is a field-dependent factor and approximates to 1 in typical memory applications [10].…”

“…Tunneling oxide charge generation during cycling is modeled according to [10], which can be applied to a nonconstant current stress over a large range of oxide thickness. This process is modeled by…”